1. Field of the Invention:
This is a novel process which produces 2-(.alpha.-hydroxymethylalkyl)-2-oxazolines and 2-alkenyl-2-oxazolines in high yields.
2. Prior Art:
The 2-substituted-2-oxazolines form a known class of compounds. The literature is replete with information regarding methods of preparation and use of such compounds. See, for example, the following review articles: (a) Wiley et al., Chemical Reviews, Vol. 44, 447 (1949); (b) Seeliger et al., Angew. Chem. Internat. Edit., Vol. 5, No. 10 (1966); and (c) Frump, Chemical Reviews, 71, No. 5 (1971). See also the patents classified by the U.S. Patent and Trademark Office under 260/307F.
The 2-alkenyl-2-oxazolines are particularly useful compounds due to their difunctionality. Of these, the 2-vinyl- and 2-isopropenyl-2-oxazolines are perhaps two of the more useful compounds due to their reactivity in vinyl polymerizations. 2-Isopropenyl-2-oxazoline, for instance has a reactivity much like an acrylate in vinyl polymerizations.
Prior art methods of preparing 2-alkenyl-2-oxazolines have heretofore utilized relatively expensive reagents in multistep processes and the product yield was normally low. See, for example, the processes described in the above review articles and refer to the following U.S. Patents Nos.: 2,831,858; 2,968,657; 3,248,397; 3,466,308; 3,505,297; 3,523,123; 3,535,332; 3,661,922; 3,678,065; 3,839,350; French Pat. No. 1,557,954 and German Offen. No. 2,302,168.
The teachings of U.S. Pat. Nos. 3,535,332, 3,661,922, 3,839,350 and French Pat. No. 1,557,954 are of particular interest relative to the instant process. Each of these references teach that 2-hydroxyalkyl-2-oxazolines can be prepared by reacting a 2-alkyl-2-oxazoline with formaldehyde and that such compounds can be subsequently dehydrated to form the 2-alkenyl-2-oxazolines. In these reactions, the 2-hydroxyalkyl-2-oxazolines were prepared by reacting a 2-alkyl-2-oxazoline with an excess of formaldehyde even though the broad teachings indicated that equimolar amounts of reactants could be used. The disclosure in U.S. Pat. No. 3,523,123 is similar in this regard. The dehydration of the 2-hydroxyalkyl-2-oxazolines was thermally and/or catalytically induced. French Pat. No. 1,557,954 is the only reference which in fact shows the preparation of 2-isopropenyl-2-oxazoline; a compound which (along with 2-vinyl-2-oxazoline) is unique among other 2-alkenyl-2-oxazolines due to its extremely high reactivity.